AI agents use different architectures depending on what they need to do.

Reactive agents respond instantly to what’s happening now. No memory. No planning. Just stimulus-response. A robot vacuum avoiding obstacles works this way. Fast but simple.

Deliberative agents think ahead. They build mental models. They plan multiple steps. Like a chess player considering future moves. Slower but smarter.

Hybrid agents combine both. Quick reflexes for urgent stuff. Deep thinking for complex problems. Self-driving cars use this: react to obstacles instantly, but plan routes carefully.

The architecture you pick depends on two things: how fast your environment changes and how complex your decisions need to be.